The imidazolinone herbicides, a potent class, have publicly known and until recently, British patent No. 2,174,395 discloses the compounds having the following formula (A). ##STR1## Wherein:
R.sup.1 is C.sub.1 -C.sub.4 alkyl;
R.sup.2 is C.sub.1 -C.sub.4 alkyl or C.sub.3 -C.sub.6 cycloalkyl;
B is CO.sub.2 R.sup.3, CONHR.sup.6, CHO, CH.sub.2 OH, COCH.sub.3, COC.sub.6 H.sub.5, CN, CH.sub.3, CH.dbd.NOH, CH.sub.2 COOH, CONHOH, CHROH, CH.sub.2 CH.sub.2 COOH, ##STR2## (wherein, R.sup.3 is hydrogen, dialkylimino, substituted alkyl, alkenyl or cation, R.sup.6 is hydrogen, hydroxy or alkenyl) A is hydrogen, COR.sup.4, SO.sub.2 R.sup.5, etc.
The above patent introduces many a herbicidal compounds, but they have recognized a disadvantage in that except for soybean, such compounds failed to exert an effective selectivity of herbicidal activity as herbicide.
Also, such imidazolinone compounds are specified in the following patents, say, German Patent No. 2,833,274, U.S. Pat. Nos. 4,824,466/4,851,021/4,824,474, European Patent No. 41,623/298,029/322,616.
However, the current situation is that the undesirable vegetation should be controlled so as to improve the growth of useful crops such as corn, rice, cotton, wheat, and soybean. The failure to check the weed growth in such useful crops may bring about significant losses to farmers and to consumer as well. Thus, the continuous research to develop more effective products should be required for a good harvest.